1. Field of the Invention
The present invention relates to an apparatus for the monitoring of a protection region comprising a monitoring unit for the detection of an object penetrating into the protection region, with the monitoring unit having at least one output at which a control signal for the excitation of a device to be monitored, in particular a switching signal for the switching off of the device, can be produced when an object penetrates into the protection region, and comprising at least one connection for a switch, in particular for an emergency off switch, through which the device can be excited, in particular switched off.
2. Description of the Prior Art
Protection regions of dangerous machines are usually made secure with apparatuses of this kind. Among these are for example pressing, cutting and planing machines as well as other machines in which automated movement sequences of parts of the machine are present within the protection region.
In order also to enable a manual switching off, for example via an emergency off switch, in apparatuses of this kind in addition to the switching off of the monitored device through the generation of a corresponding switch-off signal by the monitoring unit, for example the switching output of the monitoring unit and the output of the emergency off switch are led to a common switching element, through which both the signals which come from the emergency off switch and the signals coming from the switching output of the monitoring unit are checked. As soon as one of the two signals is recognized by the switching unit as a switching signal, a corresponding switch-off signal is generated at the output of the switching unit and is transmitted to the apparatus to be monitored, so that the latter is switched off.
Disadvantageous in this is that the switching element must satisfy specific safety requirements depending on the field of use and therefore usually has a non-negligible share of the costs in the total costs of a corresponding monitoring apparatus. Moreover, through the additional insertion of a switching element into the switch-off path there is the danger that the individual elements are connected together in an incorrect manner, through which the capability of functioning of the apparatus would not be ensured. Precisely this must be excluded however in the initially named safety-relevant monitoring apparatuses.
Since the switching unit is usually arranged at a relatively large distance from the device to be monitored, but the emergency off switch must however be provided near the potential danger location, i.e. in the region of the device to be monitored, the connection line between the emergency off switch and the switching unit often has a relatively great length. This is disadvantageous since the costs for the line, which must correspond to the prescribed safety requirements, are thereby increased and moreover the danger of a damage to the line increases.
The object of the invention is to provide an apparatus of the initially named kind which is simple and economical to manufacture and in which a faulty switching of the individual components is practically excluded.
Starting from an apparatus of the initially named kind this object is satisfied in accordance with the invention in that the connection is designed as input of the monitoring unit and in that through actuation of a switch which is connected to the input the control signal for the device to be monitored can be generated at the output of the monitoring unit.
Thus in accordance with the invention the function inherent in the monitoring unit is also used during the actuation of a switch which is connected to the input of the monitoring unit, for example an emergency off switch, to generate a corresponding control signal for the excitation of the device to be monitored. In this way an additional, reliable switching unit for the sampling of the output signals of the monitoring unit and of the emergency off switch can be dispensed with, since the control signal which is present at the output of the monitoring unit is generated by the same section of the monitoring unit both during the detection of an object which penetrates into the protection region and through actuation of the emergency off switch.
Furthermore, a faulty connection of the individual components is practically excluded in the apparatus which is designed in accordance with the invention since the monitoring unit is connected up in the usual way and the emergency off switch needs merely be connected up to a correspondingly designated input of the monitoring unit.
Since the monitoring unit is naturally arranged in the immediate vicinity of the device to be monitored and also the emergency off switch, as initially mentioned, must be provided close to this device, the connection line between the emergency off switch and the monitoring unit can be kept relatively short with an apparatus in accordance with the invention. Thus, on the one hand, the costs for the monitoring line can be reduced and, on the other hand, the danger of a damaging of the line can be reduced.
If the terms xe2x80x9cemergency off switchxe2x80x9d and xe2x80x9cswitch offxe2x80x9d are predominantly used in this application, then this is meant merely by way of example. The idea of the invention is however not restricted to this embodiment, but rather also comprises the cases in which for example a control signal is generated instead of a switch-off signal through which the device can be correspondingly excited. For example the speed of rotation of a monitored machine can be merely reduced or other control processes, such as the closing or opening of a door, can be triggered by the control signal. In the emergency off switch it can also be a matter of a continuously switching switch, so that here not only the switch states xe2x80x9con/offxe2x80x9d but rather continuous switching states can be possible.
In accordance with an advantageous embodiment of the invention the monitoring unit has a large number of inputs at which a large number of switches can be connected up. The invention is thus not restricted to the use of a single switch, but rather a plurality of switches can be provided, which for example are provided at different locations for the generation of the switching signal.
The monitoring unit is preferably designed as a contactlessly acting monitoring unit, in particular as a light grille. Contactlessly acting monitoring units are particularly advantageous since as a rule they operate without maintenance and are not mechanically stressed during the penetration of an object into the monitoring region, through which the probability of a defect can be reduced. In principle it is however also possible to design the monitoring unit as a mechanically responding monitoring unit, in particular with a tread mat for the detection of objects penetrating into the monitoring region or in another suitable manner.
In accordance with a further advantageous embodiment of the invention the monitoring unit comprises an emitter element for the emission of an emitter signal and a receiver element which is designed for the reception of the emitter signal which is emitted by the emitter element, with the output at which the switching signal is generated being provided at the receiver element. In this the connection is preferably designed as input of the receiver element.
Through the design of the connection as input of the receiver element a particularly simple embodiment of the apparatus in accordance with the invention is possible, since in this manner all connections are provided at the receiver element (input for the switch as well as output to the switching signal generation). A separate connection between the emitter element and the receiver element is not required in this embodiment.
In accordance with a further embodiment of the invention it is however alternatively or additionally possible that the connection is designed as input of the emitter element and that the emitter element is coupled to the receiver element for the transmission of control signals, in particular via a bus line. This design is in particular advantageous when the electric input signals are already occupied in the receiver element by other functions, such as for example protection check, command device, lamp outputs, switching outputs and so on. In contrast to this, the corresponding signal inputs at the emitter element to which the switch can be connected are often unused and/or available.
In accordance with a further advantageous embodiment of the invention the output is connected via a bus line to a reliable control system with a bus connection, via which the device to be monitored can be excited. This embodiment is useful in particular when the emitter element is connected to the receiver element via a bus line so that the switch can be connected up at an input of the emitter element. In principle however this embodiment is also possible when the switch is connected at an input of the receiver element or when a switch is connected at the receiver element and a switch is also connected at the emitter element.
In accordance with a further preferred embodiment of the invention the connection is designed as a multiple function connection, for example for the connection of a restart key, a clocked control system, an operating mode selection switch, a memorizing switch or for operation as a switching or report output or as synchronization connection for a plurality of monitoring units which are connected together. Through the use of multiple function connections a very variable use of an apparatus which is designed in accordance with the invention is possible. The multiple function connections can be switched and used both as input and also as output through corresponding configuration of the monitoring unit so that depending on the requirements an emergency off switch can in accordance with the invention be connected at one or more of the multiple function connections. Through this the reliability of a corresponding apparatus can be further increased.
FIG. 1 illustrates a monitoring apparatus in accordance with the prior art,
FIG. 2 illustrates a first embodiment of a monitoring apparatus which is designed in accordance with the invention,
FIG. 3 illustrates a further monitoring apparatus in accordance with the prior art, and
FIG. 4 illustrates a further embodiment of a monitoring apparatus which is designed in accordance with the invention.